<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .main {
            display: flex;
            background-color: coral;
            /* flex-direction: row;
            flex-wrap: wrap; */
            /* flex-flow: column wrap; */
            /* flex-grow: row wrap; */
            /* width: 500px; */
            height: 500px;
            /* justify-content: space-evenly;
            flex-wrap: wrap;
            align-content: space-evenly; */
            /* align-content: flex-start; */
            align-content: center;
            align-items: center;
        }

        .main div {
            width: 100px;
            height: 100px;
            background-color: rgb(173, 35, 35);
            font-size: 28px;
        }
    </style>
</head>

<body>
    <div class="main">
        <div>1</div>
        <div>2</div>
        <div>3</div>
        <div>4</div>
        <div>5</div>
        <div>6</div>
    </div>
</body>

</html>